Protective means for polyphase circuits



April 7, 1931. A. SIMON v PROTECTIVE MEANS FOR POLYPHASE CIRCUITS Filed May 12 l/VVENTOR A TTORNEY Patented Apr. 7, 1931 UNITED STATES PATENT OFFICE ARTHUR SIMON, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO CUTLER-HAMMER, INC., A CORPORATION OF DELAWARE PROTECTIVE MEANS FOR, POLYPHASE CIRCUITS Application filed May 12,

This invention relates to protective means for polyphase alternating current circuits.

An ObJECl} of the invention is to provide an improved protective device responsive upon either phase failure or phase reversal.

A further object is to provide such a device which will afford phase failure protection of a motor circuit should phase failure occur while the motor is running.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates one embodiment of the invention which will now be described, it being understood that the invention may be embodied in other forms falling within the scope of the appended claims.

In the drawing Figure 1 is a sectional view of a device incorporated in the protective means illustrated, and

Fig. 2 is a diagrammatic view of the complete protective means applied to a motor circuit.

Referring to the drawing, the protective means illustrated therein is designed for a three phase circuit and comprises a rotatable and tiltable disk 1 preferably of magnetic material subjected to influence by the mag netic fields of three electromagnets 2, 3 and 4 to be respectively connected in series with the three phases of the controlled circuit.

The disk 1 is supported on the end of a spindle 5 carried by a base 6, said disk having an open bearing 7 of any preferred form to receive the end of spindle 5 and to enable said disk to be rotated on said spindle or tilted with respect to the latter. The disk which carries a contact 8 adjacent its periphery and a centrally located contact 9, is balanced to normally assume a horizontal position and is biased to rotate in one direction by a spring 10 coiled about spindle 5. the biased movement of said disk being limited, as-will appear.

The contact 8 on the disk is provided for engagement with a stationary contact 11 carried by a bracket arm 12 fixed to base 6 and said disk is biased by spring 10 to engage said contacts. The contacts 8 and 11 thus limit rotation of the disk under the bias of 1928. Serial No. 277,244.

its spring, whereas forlimiting rotation of the disk in a reverse direction said disk is provided with an insulating bracket arm 12.

The contact 9 on the disk is provided for engagement with a contact 14 carried by a bracket arm 15 fixed to base 6, contact 14 being arranged to be engaged by contact 9 when the disk is in a horizontal position and to be disengaged by contact 9 upon tilting of the disk. Accordingly as the disk may be subjected to tilting pull at any one of a number of points circumferentially thereof the contacts 9 and 14 are preferably provided with rounded engaging portions. Also at least one of said contacts is preferably yieldingly mounted. As shown, the contact 9 is reciprocably mounted in a socket 16 and provided with a spring 17 to press the same outwardly.

The electromagnets 2, 3 and 4 which are shown mounted on base 6 are arranged about the axis of the disk equidistantly and near the periphery of said disk whereby when all are energized in a given rotation they will subject the disk to a torque acting with spring 10 to hold the contacts 8 and 11 in engagement. On the other hand. if the electromagnets are energized in a different rotation they will subject the disk to a reverse torque and thereby disengage contacts 8 and 11. Moreover, if while contacts 8 and 11 are engaged the magnetic fields of the electromagnets become unbalanced, as for example by failure or substantial reduction of current in one or two phases the disk will be tilted to disengage contacts 9 and 14. 7

Thus, as will be apparent, the device described may be employed as depicted in Fig. 2 to afford phase reversal and phase failure protection of a motor circuit. In this figure pin 13 to engage there is shown diagrammatically a motor M to be connected to a three phase supply cir cuit'L L L through an electroresponsive thr e pole main switch 20 to be controlled by the device aforedescribed which has its electromagnets 2, 3 and 4 connected between the motor and lines L L and L, respectively.

More particularly, the main switch 20 has its winding subjected to control by both sets of contacts of the aforedescribed device, said contacts being in series between said winding and one of its line connections. As illustrated the circuit of the main switch winding extends from line L by conductor 21 to bracket arm 15 and thence through contacts 14 and 9, disk 1 and contacts 8 and 11 to and through bracket arm 12 by conductor 22 through a starting push button switch 23 and a stopping push button switch 24 by conductor 25 to and through said winding to line L. This circuit provides for energization of the main switch to connect motor M in circuit and said main switch in responding engages auxiliary contacts 26 to complete a maintaining circuit for its winding extending from conductor 22 by conductor 27 through said auxiliary contacts 26 by conductor 28 to a point between push button switches 23 and 24.

Accordinglyboth sets of contacts of the device of Fig. 1 are included in series in the maintaining circuit of the main switch as well as in the energizing circuit thereof so that disengagement of either set of said contacts through phase failure or phase reversal will eiiect deenergization of the main switch and consequent disconnection of the motor.

As will be understood, the motor may upon phase failure after starting tend to run single phase and hence tend to maintain the aiiected electromagne'ts energized, but under such conditions the magnetic fields of said electromagnets will become unbalanced, which, as

i aforestated, will eii'ect tilting of disk 1 to disengage contacts 9 and 14 and this will do energize the main switch.

It is of course to be understood that the device of Fig. 1 may be modified in yarious respects, as for example by providing the same with electromagnets of the horseshoe type and varying the number of electromagnets in accordance with the circuit to be protected. Also, it is to be understood that the disk 1 might be made of copper or other conducting material. in which case it would be rotatable by the electromagnets as described but tilted through electromagnetic repulsion instead of magnetic attraction.

. What I claim as new and desire to secure by Letters Patent is:

1. The combination with a polyph ase alternating current circuit, of electromagnets connected in different phases of said circuit, there being at least one such electromagnet for each phase, and means including a member subjected to influence by the magnetic fields of all of said electromagnets for controlling the continuity of said circuit, said member being responsive to unbalancing of the individual magnetic fields of said electromagnets as by partial phase failure only, and also to reversal of their resultant field upon phase reversal, to efi'ect interruption of said circuit.

2. The combination with a polyphase alternating current circuit, of electromagnets connected in different phases of said circuit, there being at least one such electromagnet for each phase, and means including a member sub jected to influence by the magnetic fields of all of said electromagnets for controlling the continuity of said circuit, said member being responsive to unbalancing of the individual magnetic fields of'said electromagnets, as by failure of only one phase, and also to reversal of their resultant field upon phase reversal, to effect interruption of said circuit.

3. The combination with a polyphase alternating current circuit, of electromagnets connected in different phases of said circuit, there being at least one such electromagnet for each phase, and means including a rotatable and tiltable disk subjected to influence by the magnetic fields of all of said electromagnets for controlling the continuity of said circuit, said means acting upon tilting of said .disk or rotation thereof in a given direction to effect interruption or" said circuit.

4:. The combination with a polyphase alternating current circuit, of electromagnets connected in different phases of said circuit, there being at least one such electromagnet for each phase, and means including a rotatable and tiltable disk subjected to influence by the magnetic fields of all of said electromagnets for controlling the continuity of said circuit, said disk being subjected to torque reversal by phase reversal and being tiltable by unbalancing oi the magnetic fields of said electromagnets and said means acting upon rotation of said disk in a given direction or upon tilting thereof to eiiect interruption of said circuit.

5. Protective means for polyphase circuits comprising a rotatable and tiltable disk, a plurality of electromagnets to subject said disk to torque reversals under given conditions and to tilt said disk under other conditions and a. plurality of sets of contacts associated with said disk to be influenced selectively by rotation and tilting of said disk.

6. Protective means for polyphase circuits comprising a rotatable and tiltable disk,a plurality of electromagnets to subject saidv disk to torque reversals under given conditions and to tilt disk under other conditions, a set of contacts associated with said disk to he engaged and disengaged by rotation of said disk in reverse directions and a second set of contacts associated with said disk to be engaged and "disengaged according to the angular position of said disk.

7. The combination with a polyphase alternating current circuit, of electromagnets con' tacts associated therewith, for controlling the continuity of said circuit, said disk being subjected to influence by the magnetic fields of said electromagnets to be rotated thereby 5 under given conditions for actuation of certain of said contacts and tilted under other conditions for actuation of other of said contacts to render said means effective to interrupt said circuit.

8. The combination with a polyphase alternating current circuit, of means to control the continuity thereof including a plurality of electromagnets connected in different phases of said circuit,- there being at least one such electromagnet for each phase and a rotatable and tiltable disk of magnetic material subjectcd to influence by the magnetic fields of said electromagnets to be rotated and tilted selectively under difierent condi- 2Q tions of said magnetic fields.

In witness. whereof, I have hereunto subscribed my name.

ARTHUR SIMON. 

